Thermoplastic compositions

ABSTRACT

A HIGH SOFTENING THERMOPLASTIC COMPOSITION DERIVED FROM ACRYLONITRILE, N-ARYL MALEIMIDE AND AN AROMATIC OLEFIN IS (I) A GRAFT COPOLYMER (A) COMPRISING A DIENE RUBBER SUBSTRATE AND A SUPERSTRATE RESIN OF 1 TO 50% ACRYLONITRILE, 1 TO 50% N-ARYL MALEIMIDE AND 1 TO 98% AROMATIC OLEFIN; (II) A BLEND OF THE GRAFT COPOLYMER (A) WITH ACRYLONITRILE/AROMATIC OLEFIN RESIN; (III) A BLEND OF GRAFT COPOLYMER (A) WITH A COMPATIBLE RESIN; (IV) A BLEND OF GRAFT COPOLYMER (A) WITH AN ABS RESIN; OR (V) A BLEND OF A RESIN OF 1 TO 50% ACRYLONITRILE, 1 TO 50% N-ARYL MALEIMIDE AND 1 TO 95% AROMATIC OLEFIN WITH AN ABS GRAFT COPOLYMER. THE GRAFTS AND THEIR BLENDS CAN BE USED TO MAKE SHAPED ARTICLES HAVING GOOD RESISTANCE TO IMPACT.

United States Patent 3,652,726 THERMOPLASTIC COMPOSITIONS Eric Nield, Watton-at-Stone, and John Brewster Rose, St.

Albans, England, assignors to Imperial Chemical Industries Limited, London, England.

No Drawing. Continuation-impart of application Ser. No.

447,971, Apr. 14, 1965. This application May 17, 1968, Ser. No. 729,891

Claims priority, application Great Britain Apr. 21, 1964, 16,502/64; Nov. 6, 1964, 45,289/64; May 22, 1967,

Int. Cl. C08f 17/00 US. Cl. 260-876 7 Claims ABSTRACT OF THE DISCLOSURE A high softening thermoplastic composition derived from acrylonitrile, N-aryl maleimide and an aromatic olefin is (i) a graft copolymer (a) comprising a diene rubber substrate and a superstrate resin of 1 to 50% acrylonitrile, l to 50% N-aryl maleimide and 1 to 98% aromatic olefin; (ii) a blend of the graft copolymer (a) with acrylonitrile/aromatic olefin resin; (iii) a blend of graft copolymer (a) with a compatible resin; (iv) a blend of graft copolymer (a) with an ABS resin; or (v) a blend of a resin of 1 to 50% acrylonitrile, 1 to 50% N-aryl maleimide and l to 95% aromatic olefin with an ABS graft copolymer. The grafts and their blends can be used to make shaped articles having good resistance to impact.

This is a continuation-in-part of US. application Ser. No. 447,971, filed Apr. 14, 1965, now abandoned.

The present invention relates to modified polymers of acrylonitrile. Polyacrylonitrile may be formed by polymerisation in bulk, solution or aqueous suspension and is a useful fibre-forming material of high softening point and good resistance to a wide variety of chemicals. However, its wider use as a material for fabricating in molten form, eg in melt-extrusion or injection moulding processes, is restricted by its poor thermoplasticity even at temperatures as high as 250 C.; thus, it is mouldable only with the use of high pressures and at temperatures at which degradation may occur. Moreover, articles moulded from the polymer tend to shatter, breaking at a stress often as little as 2 kg./mm. and seldom more than 4 kg./ mm. when tested for flexural strength at C.

It has been proposed to modify the properties of acrylonitrile polymers by adding other copolymerisable monomers to the polymerisation reaction. Vinyl chloride, vinylidene chloride and butadiene are common examples of such monomers. While the products may be less brittle and easier to mould, they generally suffer from low softening point or low modulus. Thus they are generally unable to withstand temperatures as high as 100 C. or are unable to yield rigid articles on moulding.

It has now been found that acrylonitrile polymers with improved moulding characteristics, high softening point (generally of the order of 100 C. or above) and useful physical properties may be obtained by copolymerising acrylonitrile with certain N-substituted maleimides by free-radical catalysis.

The novel copolymers of the present invention contain from 1 to 99 mole percent of acrylonitrile and from 99 to 1 mole percent of at least one N-aryl maleimide.

The N-aryl maleimides are conveniently obtained from anilines (primary arylamines). Many different anilines are readily available and yield N-aryl maleimides that may be used as comonomers for the novel copolymers.

3,652,726 Patented Mar. 28, 1972 "ice The aryl substituent is derived from an aromatic hydrocarbon or heterocycle in which one or more of the hydrogen atoms may be replaced by other atoms or groups. Substituents containing active hydrogen atoms, however, are generally to be avoided because they may interfere with polymerisations catalysed by free radicals. The aryl groups that may be present in the N-aryl maleimides include for example, phenyl, 4-diphenyl, l-naphthyl, all the mono and di-methylphenyl isomers, 2,6-diethylpheny1, 2-, 3- and 4chlorophenyl, 4-bromophenyl and other monoand di-halophenyl isomers, 2,4,6-trichlorophenyl, 2,4,6tribromophenyl, 4-n-butylphenyl, 2-methyl-4-n-butyl-phenyl, 4-benzylphenyl, 2-, 3- and 4-methoxyphenyl, 2- methoxy-S-chlorophenyl, 2-methoxy-5-bromophenyl, 2,5- dimethoxy-4-chlorophenyl, 2-, 3- and 4ethoxyphenyl, 2,5- diethoxyphenyl, 4 phenoxyphenyl, 4 methoxycarbonylphenyl, 4-cyanophenyl, 2-, 3- and 4-nitrophenyl and methyl-chlorophenyl (2,3-, 2,4-, 2,5- and 4,3-isomers). The N-(o-substituted phenyl) maleimides are generally less coloured than the other isomers or the unsubstituted com.- pounds and may therefore be preferred if a relatively colourless product is desired.

In general, the inclusion of small amounts of N-aryl maleimides in the copolymer increases its solubility, the stress at which it breaks, and its ease of moulding. Copolymers containing at least 10 mole percent of N-aryl maleimide are mouldable or extrudable at temperatures as low as 240 C. to give transparent products. However, with very large amounts of N-aryl maleimide in the copolymer, the products tend to become more brittle again and less easy to fabricate without concomitant decomposition. Those containing from 10 to 60 mole percent of N-aryl maleimide are therefore preferred.

The copolymers may be formed by mixing the monomers together, preferably in a liquid diluent, and carrying out the polymerisation using the appropriate techniques for polymerisations catalysed by free radicals. This is conveniently done in aqueous suspension, although organic dispersions may be used. Temperatures of from 20 C. to +120 C. are generally suitable. The lower limit of temperature is set by the solidification temperature of the imide in the absence of a diluent, or by the freezing point of the diluent used or the temperature at which the reagents crystallise from solution. Increase in temperature generally yields products of reduced molecular Weight, thus in practice setting the upper limit.

The polymerisation is suitably carried out by charging a vessel with water and active ingredients, purging air from the system and bringing the vessel to the required polymerisation temperature. After polymerisation has ceased, the copolymers may be isolated from the polymerisation medium, freed from residual monomers, and dried.

The monomer composition of the polymerisable mixture is not necessarily the same as that of the isolated copolymer, because the reactivities of the monomers may differ and may vary differently with reaction conditions. To achieve a copolymer containing approximately from 10 to 60 mole percent of N-aryl maleimide residues, for example, the polymerisable mixture should comprise from 8 to 40 mole percent of N-aryl maleimide and from 60 to 92 mole percent of acrylonitrile.

The novel copolymers are usually transparent and soluble in the usual solvents for polyacrylonitrile. They have full Vicat softening points ranging from about C. to at least 250 C. The copolymers containing 10 mole percent or more of imide residues are readily mouldable materials generally having softening points of from about 115-l50 C., depending on the particular imide and its concentration. However, even these preferred copolymers still tend to become more viscous while they are held for long periods of time at elevated temperatures, such as would be used for example in a moulding or extrusion operation.

According to the invention, modified copolymers of acrylonitrile and N-aryl maleimide which have little or no tendency to become more viscous when molten (and are therefore more attractive as moulding and extrusion materials) comprise from 1 to 98 mole percent of acrylonitrile, from 1 to 98% mole percent of at least one N-aryl maleimide and from 1 to 98 mole percent of at least one olefine, the quantities being chosen to total 100 mole percent. For convenience, these are referred to hereinafter as tercopolymers although they may, of course, be formed from more than three monomers. By maintaining the amount of each monomeric constituent between specified limits in the monomer mixture, strong moulding materials of high softening point may be obtained. These generally have flexural strengths better than polystyrene and have full Vicat softening points that are almost invariably above about 95 C. and may approach or even exceed 160 C. In particular, strong, high-softening polymeric materials may be formed by polymerising a mixture comprising from 20 to 90 mole percent of acrylonitrile and corre spondingly from 10 to 80 mole percent in total of N-aryl maleimide and olefine each being in an amount of at least 1 mole percent.

With the presence of the olefine, the preference for a lower limit of 10 mole percent of N-aryl maleimide for the products no longer applies, substantially lower amounts beingstill effective in the tercopolymers. For example, very attractive moulding materials have been obtained using only 5 mole percent of N-phenylmaleimide. This is quite surprising since it is known that copolymers of acrylonitrile with olefines usually have undesirably low softening points for most moulding applications.

The preferred ratios for the monomers in the tercopolymers depend upon the choice of olefine and the properties desired in the product. The initial introduction of the olefine into the polymerizable mixture (for example, the addition of up to about 20 or 25 mole percent isobutene) primarily improves the fiexural strength of the product but tends to atfect the softening point (as shown by the -fiull Vicat measurements) adversely. The ultimate effect of introducing the olefine depends upon whether it replaces the acrylonitrile or the N-aryl maleimide or both. However, tercopolymers cannot be obtained containing more than 50% molar of an alkyl-substituted ethylene which does not homopolymerise under free-radical catalysis, so for most olefines there is little point in using more than 50 mole percent in the polymerisation mixture (although for some it may be necessary to use more in order to obtain the desired amount in the polymer).

If the amount of olefine in the polymerisation mixture is increased at the expense of the imide, the polymeric product tends to show an improvement in flexural strength but a drop in softening point. On the other hand, at a constant low concentration of N-aryl maleimide (for example, generally up to about mole percent for N- phenylmaleimide), increasing the amount of olefine at the expense of the acrylonitrile again tends to reduce the softening point, but a plot of fiexural strength against olefine content passes through a maximum. For example, when 5 mole percent of N-phenylmaleimide is used with isobutene, this occurs at a point equivalent to about mole percent olefine in the monomer feed.

The N-aryl maleimide preferably constitutes not more than mole percent of the copolymer when products particularly attractive for their fiexural strength are required. Consequently, preferred tercopolymers are made by polymerising from 25 to 90 mole percent of acrylonitrile, from 1 to 25 mole percent of Naryl maleimide and from 1 to 50 mole percent of olefine, the quantities being chosen to total 100 mole percent.

Mouldable products having a very desirable combination of high softening point (of the order of about 100 C. or above) and excellent fiexural strength (up to six times that of polystyrene) are formed by polymerising a mixture comprising from 1 to 10 mole percent of at least one N-aryl maleimide, from 15 to 30 mole percent of at least one olefine and from 84 to 60 mole percent of acrylonitrile, the quantities chosen to total 100%. Preferred polymers themselves contain from 60 to mole percent of acrylonitrile, from 1 to 15 mole percent of N-aryl maleimide and from 5 to 30 mole percent of olefine. At room temperature, many of these products yield before breaking when subjected to the conditions used for measuring their flexural strength.

Suitable olefines are those copolymerisable by freeradical catalysis; examples are those containing not more than 10 carbon atoms, including alkenes such as ethylene, propylene, butene-l, isobutene, pentene-l, hexene-l, 2- methylbutene-l, Z-methylpentene-l, 4-methylpentene-1, 2,4,4-trimethylpentene-1, octene, octadecene, cyclohexene and methylenecyclohexane, dienes such as butadiene and norbornadiene, and aralkenes such as styrene, a-methyl styrene and indene. Isobutene in particular is readily available and gives tercopolymers having very good physical properties.

The tercopolymers generally have transparencies of the same order as the copolymers without olefine, and d issolve not only in the usual solvents for polyacrylomtnle but also for example in acetone, cyclohexanone and Z-chlorophenol.

The tercopolymers may be formed by the polymerisation process described above, with the addition of the olefine. When the latter is gaseous or has a high vapour pressure it may be desirable to operate the polymerisation under superatmospheric pressure, when for convenience the gaseous monomer is usually added last.

The actual amount of each constituent forming the polymerisable mixture which is intended to yield a copolymer of a given constitution depends upon the reactivity of each of the constituents when in contact with the others. For binary mixtures this may be determined readily by established techniques but for ternary or more complicated mixtures the desired amounts may be determined more quickly by experimentation.

The preferred range of reduced viscosity for the'copolymers and tercopolymers of the invention will depend to some extent upon the choice of third monomer (where present) and the ratio of monomers in the polymer. In general, those having a reduced viscosity below about 0.3 (measured on a solution of 0.5 g. of polymer in cm. of dimethylformamide at 25 C.) tend to lack the combination of physical properties desirable for moulding materials, while those of reduced viscosity above about 3 or 4 are difficult to process by currently available machinery.

The mouldable tercopolymers described above may be shaped by any suitable process in which the plastic is heated until it attains a relatively fluid state and is then subjected to a forming process. For instance, they may be injection-moulded, compression-moulded, or extruded and the articles so produced may be subjected to further fabrication processes if desired. For example, compressionmoulded or extruded sheets may be vacuum-formed into complex three-dimensional shapes. Films and sheets may be cast from the solutions of the copolymers and tercopolymers.

The copolymers and tercopolymers may be mixed with additives such as thermal stabilisers, absorbers of ultra violet light, pigments, dyes, plastici-sers, fillers (e.g. glass fibres), lubricants, processing aids and mould release agents. They may be blended with other natural or synthetic polymeric materials (e.g. rubbers) if desired. 7

It has been found that N-aryl maleimides may be polymerised with acrylonitrile in certain specified quantities to yield copolymers which may be formed readily into fibres whose longitudinal strength may be increased by stretching them. These materials may be formed according to the present invention by polymerising from 1 to 20 mole percent of N-aryl maleimide with from 99 to 80 mole percent of acrylonitrile. Particularly preferred fibre-forming copolymers are prepared by polymerising from 2 to 15 mole percent of N-aryl maleimide with from 98 to 85 mole percent of acrylonitrile.

Many attempts have been madev to improve the solubility, dye-receptivity, non-inflammability and thermal stability of polyacrylonitrile fibres by introducing small amounts of comonomers into the polymer chain. The copolymers of the invention provide fibre-forming materials which have good dye-receptivity and improved solubility compared With homopolymers of acrylonitrile and yet still retain surprisingly high softening points.

Modified fibre-forming materials, having improved breaking stress and a soft feel, may be obtained according to the invention by polymerising a mixture comprising from 98 to 80 (preferably 94 to 80) mole percent of acrylonitrile, from 1 to 14 (preferably 5 to mole percent of N-aryl maleimide and from 1 to 14 (preferably 1 to 10) moles percent of olefine, the quantities being chosen to total 100 mole percent.

These copolymers and tercopolymers may be formed into fibres by any suitable process for spinning acrylonitrile polymer, such as melt-spinning, dry-spinning or wetspinning. Spinning from solution is conveniently used because of the high melting points of the polymers. Dry spinning from a solvent is the preferred process. The drawing of the filaments so formed is generally effected at elevated temperature; they cannot be readily cold-drawn.

Homogeneous copolymers of acrylonitrile and a conjugated aromatic olefine containing not more than 50 mole percent of acrylonitrile and not more than 80 mole percent of conjugated aromatic olefine are known and may be made by simple copolymerisation of the monomers in the required proportion. Where the reaction mixture contains substantially more than 50 mole percent of acrylonitrile, the polymer initially formed will contain a proportion of aromatic olefine in excess of the proportion present in the monomer mixture. This will be at the expense of polymer formed later. Thus for a given monomer composition containing substantially more than 50 mole percent acrylonitrile the overall composition of the polymer might be the same as that of the monomer mixture, but the polymer will not be homogeneous, that formed earlier being higher in olefine than that formed later. Similarly where a monomer mixture contains more than 80 mole percent of conjugated aromatic olefine, the polymer initially formed will be proportionally richer in acrylonitrile. The intermediate range may be termed the azeotropic range within which the comonomers polymerise to give a copolymer containing the aromatic olefine and acrylonitrile units in substantially the same proportion as they were in the monomer mixture, thereby forming homogeneous copolymers.

Such azeotropic copolymers of acrylonitrile and styrene are widely used as thermoplastic resins and in the rubber-containing materials known generally as ABS materials.

The resins are strong and transparent, and the ABS materials are remarkably tough, but they both suffer from relatively low softening points, making ABS unsuitable for example for hot water pipes. It has been found that this deficiency may be overcome by incorporationg an N-aryl maleimide into the azeotropic copolymers of acrylonitrile and conjugated aromatic olefine, according to the present invention.

Accordingly we provide a copolymer whose units comprise 1-50 mole percent of acrylonitrile, 1-98 mole percent of at least one conjugated aromatic olefine and 1-50 mole percent of at least one N-aryl maleimide and in which the molar ratio of styrene to acrylonitrile lies within the range 0.5-4. The preferred composition range is 50 mole percent acrylonitrile, -80 mole percent of at least one conjugated aromatic olefine and 1-20 mole percent of at least one N-aryl maleimide. The composition which is particularly preferred is substantially about 40 mole percent acrylonitrile, about 55 mole percent of at least one aromatic olefine and about 5 mole percent of at least one N-aryl maleimide. These will be referred to herein as terpolymers even though more than three monomers may be used, eg more than one olefine may be polymerised.

The conjugated aromatic olefine is selected from those of the formula CH CRAr, and also acenaphthylene, indene and coumarone. In this formula R is hydrogen or methyl and Ar is an optionally ring-substituted residue of aromatic character having not more than 3 rings and each substituent (if any) having not more than 4 carbon atoms. Examples of such olefines include styrene, a-methylstyrene, u-ethylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-chlorostyrene, m-chlorostyrene, pchlorostyrene, 2,5-dimethylstyrene, 1 vinylnaphthalene, ar-dibromostyrene, and N-vinylcarbazole, either singly or together with one or more such olefines. Of these the preferred olefines are styrene and a-methylstyrene. Where the use of styrene is described herein, a-methylstyrene or a mixture of the two may be used instead if desired.

The invention has been described with reference to acrlonitrile terpolymers. In all cases the acrylonitrile may be replaced in part or completely by methacrylonitrile.

The terpolymers may be moulded to give strong, transparent plaques. They may be mixed with additives such as thermal stabilisers, absorbers of ultraviolet light, pigments, dyes, plasticisers, fillers (e.g. glass fibres), lubricants, processing aids and mould release agents. As with styrene/acrylonitrile resins the terpolymers of the present invention may be blended with other natural or synthetic polymeric materials, in particular rubbers to produce a tougher material. The invention may therefore be used for providing an ABS-like material of higher softening point.

The terpolymer is not limited to use as the resin itself. By carrying out the copolymerisation in the presence of a diene rubber, a graft copolymer may be formed in which the superstrate is a terpolymer according to the present invention. Thus in addition to uses as the terpolymer itself, applications include blends of terpolymer resin and .ABS graft, terpolymer graft, blends of terpolymer resins and terpolymer grafts, and blends of terpolymer grafts with compatible resins. The amount by which the softening point is raised will depend on the maleimide and the proportions used. It will also depend on whether the maleimide is used in the resin, the graft superstrate, or in both the resin and graft superstrate; generally it is more effective in the resin than in the graft alone.

By the term ABS graft polymer we mean those comprising a substrate of a diene rubber and a superstrate of styrene and acrylonitrile in which the molar ratio of styrene/acrylonitrile lies within the range 0.5-4. The terpolymer grafts are those in which the superstrate also contains 15O mole percent N-aryl maleimide as described for the copolymer above.

The diene rubber contains from 40% to molar of at least one conjugated 1,3-diene monomer and from 0% to 60% molar of at least one other ethylenically unsaturated monomer copolymerisable with free radical catalysts. Suitable dienes include for example butadiene, isoprene, 2,3-dimethylbutadiene, piperylene and chloroprene. A wide variety of other monomers may be used; including aralkenes such as styrene and a-methylstyrene, esters of acrylic and methacrylic acids such as methyl, ethyl, n-butyl and Z-ethylhexyl acrylates and methyl and n-butyl methacrylates, esters of fumaric acid, and unsaturated nitriles such as acrylonitrile; styrene and acrylonitrile are particularly convenient.

Graft copolymers may be made by a sequential polymerisation in which the monomers for the superstrate are polymerised by free radical catalysts in bulk or in a liquid diluent containing the substrate rubber in suspension or solution. The polymerisation is conveniently carried out in an aqueous emulsion, although suspension or bulk 7 polymerisations may also be used, in combination if desired.

The graft copolymer thereby produced may be isolated from the polymerisation medium, freed from residual monomers, and dried. For some purposes it can then be used directly in the fabrication of shaped structures or coatings; this is particularly true of the grafts containing relatively small amounts of rubber. An important use for grafts is in blending with compatible resins so as to improve their impact resistance. A particularly suitable resin for this purpose is one made as described above for the graft but omitting the rubber.

When both the graft and the resin required for blend ing are available as latices (e.g. as the products of an aqueous emulsion polymerisation), the components need not be isolated but the latices can be mixed, i.e. the graft and the resins are latex-blended. After adding any re quired additives, e.g. stabilisers and antioxidants, the blend is then coagulated by pouring into a dilute electrolyte solution, e.g. aluminium sulphate or calcium chloride solution, and the product isolated and washed with hot water.

Alternatively the two components may be melt-blended on a mill having heated rollers, or in an extruder.

A product in many ways equivalent to a blend may also be obtained directly by adjusting the conditions of the grafting polymerisation so that some of the superstrate monomers copolymerise to give some separate resin as well as the graft; thus the graft is produced concurrently with the resin.

The toughness of the final blended composition is governed not only by the amount of rubber it contains (preferably 1% to 50% by weight) but also by the proportion of superstrate in the graft used for blending.

The grafts or their blends, mixed with any desired fillers or reinforcing materials, lubricants and stabilisers, can be used as thermoplastic raw material to make articles which require a good resistance to impact. Their toughness coupled with high strength and high softening point may thus be displayed to advantage. For example, the compositions may be extruded into sheet or tube, and the sheet can be calendered with embossing if desired or can be shaped as required e.g. by pressing, drawing or vacuumforming. The compositions can also be compressionmoulded and injection-moulded. Examples of articles that may thus be produced using the compositions of the invention include panelling and exterior casing for machinery (as in motor cars, office machines and household equipment), crash helmets, pipes for conveying fluids, and telephone receivers. The use of compositions of the invention having superior tensile strength coupled with toughness and rigidity may allow economy of material in comparison with currently used products in that thinner pieces would serve the same purpose. The advantageous physical properties of the compositions may also permit them to be used in engineering applications for which plastics have not hitherto been suitable.

The terpolymer or graft may similarly be blended with other compatible polymer e.g. PVC, chlorinated PVC, bisphenol A polycarbonate, or polymethylmethacrylate. Thus a tough, high-softening PVC may be produced by blending PVC with a terpolymer graft as described above.

The following examples illustrate the invention. In the examples, except where otherwise indicated, all parts are expressed as parts by weight, the reduced viscosity was measured on a solution of 0.5 g. of polymer in 100 cm. of dimethylformamide at 25 C., the melt viscosity was measured at 260 C. at a shear rate of 1000/sec., and the flexural breaking stress and tensile yielding stress were measured at C.

The flexural breaking stress was measured on specimens 51 mm. long and 12.7 mm. wide milled from a compression-moulded sheet 3 mm. thick. The specimen rested on two supports 38.1 mm. apart and midway between them a load was applied sufficient to bend the specimen at the rate of 457 nun/min. The flexural breaking stress was calculated by multiplying the load at the moment of rupture by the factor: (l.5)(38.1)/(12.7) (3) =0.5.

The tensile yielding stress was measured on specimens 76 mm. long and 14 mm. wide milled from a compression moulded sheet 3 mm. thick. The cross-sectional area across the centre of the specimen was reduced to 9 mm. by milling two slots (radius of curvature 31 mm.) oppo site each other in the long edges so that the narrowest width of the specimen was 3 mm. A tensile stress was then applied to the specimen sufficient to elongate it at the rate of 12.7 min/min. and the stress at the yield point (or brittle fracture) was recorded.

In the notched specimen impact test, carried out at 20 C., a specimen 60 mm. long, 6.5 mm. wide and 3 mm. thick was given at 45 notch 2.5 mm. deep (tip radius not greater than 0.25 mm.) in the centre of one edge. It was supported between two supports 50 mm. apart and struck centrally on the edge opposite the notch by a pendulum dropping from 300 mm. with more than sufficient energy to break the specimen. From the residual energy of the pendulum the energy required to break the specimen was calculated and divided by the cross-sectional area of the specimen at the notch. The resulting value (expressed in joules/cm?) represents the energy required to break the material.

EXAMPLE 1 10 parts (7.1 mole percent) of N-phenylmaleimide, 40 parts (92.9 mole percent) of acrylonitrile, 0.5 part of azodiisobutyronitrile and 440 parts of dry benzene were placed in a 3-neck flask fitted with a condenser, a stirrer and a nitrogen supply and the mixture was purged well with nitrogen for 5 minutes. The temperature was then raised to 60 C. and the mixture was stirred. After 4 hours a further 0.5 part of azodiisobutyronitrile was added and then the mixture was stirred at 60 C. for 16 hours followed by 6 hours at 7680 C. The resulting product was filtered off, washed with benzene and dried in vacuum to yield 33.6 parts of copolymer having a reduced viscosity of 0.69.

Oxygen analysis showed that the copolymer contained 22.7 weight percent (8.25 mole percent) N-phenylmaleimide. It could be compression-moulded at 200 C. to give transparent brown plaques having a one-tenth Vicat softening point of 98 C. and a full Vicat softening point of 121 C. The polymer as made showed little of the 2-dimensional crystallinity characteristic of polyacrylonitrile.

EXAMPLE 2 The process of Example 1 was repeated using an equal volume of methanol instead of benzene as the solvent. The polymerisation was effected at 60 C. and the product was filtered off, washed with methanol and dried in vacuum to yield 13.5 parts of polymer with a reduced viscosity of 0.4 and containing 16.8% by weight (5.8 mole percent) of N-phenylmaleimide. It was compressionmoulded at 200 C. to give transparent brown discs with a one-tenth Vicat softening point of 110 C. However, the full Vicat softening point was above 250 C., indicating a large amount of residual two-dimension crystalline order.

EXAMPLE 3 5 parts (3.3 mole percent) of N-phenylmaleimide and 45 parts (96.7 mole percent) of acrylonitrile were dispersed in 200 parts of water containing 0.25 part of potassium persulphate in the reaction vessel described in Example 1. The vessel was then purged with nitrogen and and the stress at which they underwent brittle fracture in weight percent (9.2 mole percent) of N-phenylmaleimide the fiexural test. This is shown in the following table.

by oxygen analysis.

Vicat softening point C.)

. Flexural break- One- Properties of compression ing stress tenth Full moulding (kg/mm?) Comments A 237 250 Transparent, orange. 4. 7 Could not be extruded.

B-.. 182 250 Transparent, brown. Not measured Still showed polyacrylonitrile crystalline order. O 170 21|=5 Transparent, pale brow do Still showed polyacrylonitrile crystalline order.

D, 105 7 .do 9T0 .S. Polyacrylonitrile crystalline order improved by annealing,

[EXAMPLE 4 The process of Example 3 was repeated but 100 parts of water were replaced by an approximately equal volume of methanol. The polymerisation was eifected at 60 C. for 4 hours after which the polymer was isolated by (Jentrifuging, washed with water followed by methanol and dried in vacuum. 29.2 parts of a copolymer were obtained having a reduced viscosity of 3.11 and containing 28.2

EXAMPLE 6 A series of copolymers was made by the process of Example 3 using in each case 50 parts of monomer, 0.25 part of potassium persulphate, 0.2 part of sodium dodeyl sulphate, 0.5 part of dodecanethiol and 200 parts of water. The temperature of the reaction was 60 C. and the other details of polymerisation conditions and products are set out in the table below.

Comonomers (parts by Measured by oxygen analysis.

weight percent (10.7 mole percent) of N-phenylmaleimide. The product was compression-moulded into transparent brown discs, having one-tenth Vicat and full Vicat softening points of 148 C. and 215 C. respectively. The

The addition of N-phenylmaleimide was again found to have a marked effect on the softening point and fiexural breaking stress of the products. This is illustrated in the following table.

Vicat softening Flexural breaking stress (kg/mm!) Comments point C.)

One- Properties of tenth Full compression moulding A Transparent, amber B 151 204 Transparent, pale brown O 118 128 do D 125 135 .do

2. 9 Highly crystalline. 3.0 Not extrudable without decomposition. Still crystalline. 9. 9 Extrudable at 220 C. to yield transparent extrndate; melt viscosity increases by 60% every 5 minutes at 220 C. 9.8 Amorphous. Melt viscosity increases by 100% every 5 minutes at 220 C. 11. 3 Extrudable. Melt viscosity increases by 50% every 5 minutes at 220 C.

1 Not measured.

copolymer showed strong polyacrylonitrile-type crystallinity as made and also after annealing from 150 C.

EXAMPLE 5 A series of coplymers were made by the process of Example 3 using in each case 50 parts of monomer, 0.25 part of potassium persulphate and 200 parts of water. 0.5 part of sodium dodecyl sulphate was added to aid dispersion. The temperature of the reaction was 60 C. and other details of polymerisation conditions and the products are set out in the table below.

Comparison of B with C illustrates the very marked effect on the softening point and fiexural breaking stress caused by increasing the N-phenylmaleimide content above about 10 mole percent.

EXAMPLE 7 69.2 parts mole percent) of N-phenylmaleimide and 42.4 parts '(40 mole percent) of acrylonitrile were dispersed in 300 parts of water in a small shaking autoclave. The water already contained 1.5 parts of potassium persulphate, 1.056 parts of sodium metabisulphite and Comonomers (parts by weight with mole percent Yield Reduced (percent) viscosity in brackets) N-phenyl Reaction male1m1de Acrylo- N-phenyl time, in polymer nitrile maleimide hours (mole percent) 1 Measured by oxygen analysis.

The addition of N-phenylmaleimide was found to have 0.5 part of sodium dodecyl sulphate. The autoclave was a marked effect on the softening point of the products successively pressurised with nitrogen to 10 kg./cm. and

twice with hotwater and once with ethanol, extracted with ether and finally dried in vacuum. 98.2 parts of a tercopolymer were obtained having a reduced viscosity of 9.94. It had a melt viscosity of 16 10 poises which did not increase with time. It was compression-moulded at 250 C. to give transparent amber plaques having onetenth and full Vicat softening points of 154 C. and 164 C. respectively. The flexural breaking stress was 3.3 kg./ mm.

EXAMPLE 8 The process of Example 7 was repeated using 34.6 parts mole percent) of N-phenylmaleimide, 42.4 parts (40 mole percent) of acrylonitrile, 56 parts (50 mole percent) of isobutene, 1.5 parts of potassium persulphate, 1.056 par-ts of sodium metabisulphite, and 0.667 part of sodium dodecyl sulphate in 400 parts of water. The polymerization was effected at 30 C. for 4 hours in a shaking autoclave and the product was worked up as described in Example 7 to yield 70.1 parts of a tercopolymer having a reduced viscosity of 1.0. It had a melt viscosity of 13 10 poises Which did not increase with time. The tercopolymer was compression-moulded at 250 C. to give transparent amber discs having one-tenth and full Vicat softening points of 132 C. and 144 C. respectively. The flexural breaking stress was 6.8 kg./mm.

EXAMPLE 9 The process of Example 7 was repeated using 34.6 parts (10 mole percent) of Nphenylmaleimide, 42.4 parts (40 mole percent) of acrylonitrile, 84 parts (50 mole percent) of 2-methylpentene-1, 1.5 parts of potassium persulphate, 1.056 parts of sodium metabisulphite and 0.667 part of sodium dodecyl sulphate in 400 parts of water. The process and working-up procedure were as described in Example 7 and the yield was 51.5 parts of a tercopolymer having a reduced viscosity of 0.85 and containing 29 mole percent of N-phenylmaleimide, 52 mole percent of acrylonitrile and 19 mole percent of Z-methyIpentene-l, based on infrared analysis. It had a melt viscosity of 14X 10 poises which did not increase with time. The polymer was compression-moulded to give transparent amber mouldings with one-tenth and full Vicat softening points of 150 C. and 160 C. respectively. The flexural breaking stress was 9.7 kg./mm.

EXAMPLE 10 The process of Example 7 was repeated using 34.6 parts (6.7 mole percent) of N-phenylmaleimide, 42.4 parts (26.7 mole percent) of acrylonitrile, 112 parts (66.7 mole percent) of isobutene, 1.5 parts of potassium persulphate, 1.056 parts of sodium metabisulphite and 0.667 part of sodium dodecyl sulphate in 400 parts of water. The polymerisation and work-up procedure Were as described in Example 7 and 74.2 parts of tercopolymer were obtained having a reduced viscosity of 0.84. Its melt viscosity was 85x10 poises and this did not increase with time. The tercopolymer was compression moulded to give transparent amber compression mouldings having one-tenth and full Vicat softening points of 132 C. and 143 C. The flexural breaking stress was 6.7 kg./mm.

EXAMPLE 11 The process of Example 7 was repeated using 34.6 parts (10 mole percent) of N-phenylmaleimide, 53 parts (50 mole percent) of acrylonitrile, 44.8 parts (40 mole percent) of isobutene, 1.5 parts of potassium persulphate, 1.056 parts of sodium metabisulphite and 0.667 part of sodium dodecyl sulphate in 400 parts of water. The polymerisation and working-upprocedure were as described in Example 7 and 89.3 parts of tercopolymer wereobtained, having a reduced viscosity of 0.9. Its melt viscosity was 8.0 10 poises and this did not increase with time. The tercopolymer was compression-moulded to give transparent pale yellow mouldings having one-tenth and full Vicat softening points of 122 C. and 132 C. respectively. A sample of the moulding was found to break at 8.2 kg./ mm. in the flexural test.

EXAMPLE 12 The process of Example ll was repeated using 34.6 parts 10 mole percent) of N-phenylmaleimide, 74.2 parts (70 mole percent) of acrylonitrile and 22.4 parts (20 mole percent) of isobutene. After polymerisation, purification, washing and drying, 115.6 parts of tercopolymer were ob tained having a reduced viscosity of 1.11 and contain; ing 10 mole percent of N-phenylmaleimide, 73 mole per cent of acrylonitrile and 17 mole percent of isobutene, based on infrared analysis. Its melt viscosity was x10 poises and this did not increase with time. It was compression-moulded to give transparent amber samples having one-tenth and full Vicat softening points of 119 C. and 132 C. respectively. The flexural breaking stress was 11.1 kg./mm.

EXAMPLE 13 The process of Example 11 was repeated using 17.3 parts (5 mole percent) of N-phenylmaleimide, 79.5 parts (75 mole percent) of acrylonitrile and 22.4 parts (20 mole percent) of isobutene. 98 parts of tercopolymer were obtained having a reduced viscosity of 2.14. Its melt viscosity was 12 10 poises and did not increase with time. Transparent, pale yellow compression mouldings were obtained having one-tenth and full Vicat softening points of 92 C. and 109 C. respectively, and a flexura breaking stress of 17.4 kg./mm.

EXAMPLE 14 The process of Example 11 was repeated using 20.75 parts (5 mole percent) of N-Z-chlorophenylmaleimide, 79.5 parts (75 mole percent) of acrylonitrile and 22.4 parts (20 mole percent) of isobutene. 105 parts of tercopolymer were obtained having a reduced viscosity of 1.76 and a melt viscosity of 9.5 10 poises. Transparent, al most colourless mouldings were obtained having one-tenth and full Vicat soften points of C. and 109 C. respectively, and a flexural breaking stress of 17.1 kg./mm.

EXAMPLE 151' The process of Example 7 was followed, using dodecanethiol as a chain transfer agent in the polymerisa tion mixture. 17.3 parts (5 mole percent) of N-phenyl maleimide, 79.5 parts (75 mole percent) of acrylonitrile, 1.5 parts of potassium persulphate, 1.056 parts of sodium metabisulphite, 1.29 parts of dodecanethiol, 0.667 part of sodium dodecyl sulphate and 400 parts of water were placed in a small shaking autoclave which was then perssurized to 8 kg./cm. with nitrogen and vented three times. 22.4 parts (20 mole percent) of isobutene were then added and the pressure brought to 4.5 kg./cm. with nitrogen. The mixture was shaken at 30 C. for 4.5 hours before releasing the pressure. The resulting latex was coagulated by the addition of saturated aluminum sulphate solution and the precipitated material was filtered, washed three times with hot water and twice with methanol and dried in vacuum to yield 92 parts of copolymer having a reduced viscosity of 0.99. -A sample of the polymer was compression-moulded at 200 C. to yield'very pale yellow transparent plaques having a full Vicat softening point of 102 C., a flexural breaking stress of. 17.3 kg./mm. and a melt viscosity of 5.7)(10 poises. The melt viscosity was unchanged after 5 minutes at 260 C. indicating that the polymer was wholly amorphous.

EXAMPLE 16 amount of dodecanethiol was reduced to 1.21 parts. The

monomer mixture comprised 25.95 parts (7.5 mole percent) of N-phenylmaleimide, 74.2 parts (70mole percent) of acrylonitrile and 25.2 parts (22.5 mole percent) of isobutene. 110.5 parts of copolymer were obtained having a reduced viscosity of 0.84. It Was moulded at 200 C.

to yield a pale yellow plaque with a Vicat softening point of 106 C. and a flexural breaking stress of 11.4 kg./mm. Comparison of this example with that prepared by process B of Example 18 indicates the effect on Vicat softening EXAMPLE 17 point of increasing the amount of N-phenylmaleimide at the expense of isobutene; the flexural breaking stress is The process of ExamPle was .repeated but m this not markedly inferior in this case. The beneficial effect case. PH of the meduim aqlusted to 3 4.by.the on Vicat softening point of adding still more N-phenyladdition of 0.1 N sulphuric acid prior to polymerisation. maleimide is Shown by Example 12 Where however an igig x g g 2 2:3; g g fig g f z g zggi yg fi l5 adverse effect on flexural breaking stress is also apparent.

The process of Example 15 was repeated but with the exclusion of the sodium metabisulphite and the dodecanethiol and the mixture was shaken at 60 C. for 3 hours. The latex was coagulated and the solid product worked up as described in the previous example to yield 89 parts of copolymer having a reduced viscosity of 2.48. Compression moulding produced pale yellow plaques having a full Vicat softening point of 103 C.

showed a full Vicat softening point of 101 C. and a EXAMPLE fiexural breaking Stress of Using the process of Example 15 34.6 parts (10 mole EXAMPLE 18 20 percent) of N-phenylmaleimide, 42.4 parts mole percent) of acrylonitrile and 56 parts mole percent) of A Series of polymerisations Were eafried out to Show isobutene were shaken at C. in 300 parts of water effect of Varying the amount of acfylonitrile and 01911116 containing 0.5 part of potassium persulphate and 0.5 part in h monomer mixtul'e- Each polymerisation was of sodium dodecyl sulphate. 52.9 parts of copolymer were tested in 400 parts of Water containing 3 parts of p obtained having a reduced viscosity of 0.87. It was Sium Pefslllphate, P511rts of Sodium metabisulphite, 25 moulded to give transparent plaques which were pale P Of Sodium dodecyl sulphate and Parts of brown in colour, had a full Vicat softening point of 141 decanethiol. The amount of each monomer used in each of C, d a fi ral breaking stress of 11.2 kg./mm. the polymerisations, together 'with the yield of polymer, its reduced viscosity, its Vicat softening point, its flexural EXAMPLE 21 breaking stress and other comments are set out in the fol- 30 The process of Example 15 was repeated using 0.6 lowing table. part of dodecanethiol. The polymerisation was effected A B C D E F Comonomers and amounts (expressed as parts by weight with mole percent of the monomer mixture in iiI li 1m 1 d 173 (5 7) 173 (5'7) 3 -p any aclmi e a a 17. 17.3 (5%) 17.3 (5 17.3 5

Acrylonitrile 6 74.2 79.5 84.8 90.1 (82 95.4 9 73,).

. Olefinc(1sobutene) 33.6 (30%)- 28 (25%) 22.4 (20%) 16.8 (15%) 11.2 (10%) 5.6 (5%).

Yield of polymer 99.3 parts. 101 4 parts 80.5 parts 104.0 parts 102.9 parts 103.4 parts.

Reduced VlSCOSlty 0-80 .84 0.97 0.88 1.04 1.08. Polymeric composition (mole percent):

N-phcnylmaleirnide 6.. 6 6 5 6 5. Acrylonitrile 70 71 74 77 83 87. Isobutenc 24 23 20 18 11 8. F ll Vicat softening point 98 C 102 C C 126 C 162 C. Fiexural breaking stress--- 9.6 kg,/rnm, 12.6 kgJmm 15.2 kg./mm. 14.9 kg./mm 9.8 kgJmm. 0.8 kg./mm. Crystalline order Amorphous as Amorphous as Amorphous as Amorphous as Showed low 2 Showed moderate made and when made and when made and when made but dimensional Z-dimensional annealed at annealed at annealed at developed low order as made order as made 200 C. 2 200 C. 2-dirnensional which increased which increased order on considerably considerably annealing at on annealing. on annealing.

Colour of moulding Yellow Yellow Very pale yellow" Yellow Deep yellow Deep yellow.

REFERENCE EXAMPLE 55 for 4 hours at a temperature of 29'-32 C. After precipi- The process of Example 18 was repeated using 795 tatmg, filtering, washing and drying as usual, 94.7 parts parts (75 mole percent of acrylonitrile and 28 parts (25 of a p lymer were obtained hav ng a reduced viscosity mole percent of isobutene only and in the absence of of 1.27, and containing 73 mole percent of acrylonitrile, dodecanethiol. After coagulating the latex and working 20 mole Percent of isoblltene and 7 mole Percent Of up the solid product, 89.1 parts of copolymer were ob- 50 N-phenylmaleimide. Plaques were compression-moulded tained having a reduced viscosity of 1.14. Nitrogen anal from the copolymer at 200 C. to give slightly hazed, ysis indicated that it contained 79 mole percent of acrylover pale y ll transparent mouldings having a flexural ni rile and 21 mole Percent isobutel'le- Plaques breaking stress of 17.0 kg./mm. and a full Vicat softening pression-moulded from the copolymer at 200 C.hw;;:re point f transparent and yellow in colour and while they a a 5 B way of com arison the recess was re ated usin usefully g .flexufal Freaking sire/SS the order of double the amouni of catalyst, i.e. 3.0 parts f potassiurr i l-'-g-/ then full Vlcat Sofiemng Pomt was low at 85 persulphate and 2.1 parts of sodium metabisulphite; in

C. Comparison of this copolymer with products D and all other res i pects the p1 ocess was the same. Polymerisation E of Example 18 show the marked drop in Vicat softening was effected for 4 hours at a temperature of C.

point that occurs when the N-phenylmaleimide is omitted. 70 In this case, A parts of copolymer were obtained EXAMPLE 19' having a reduced viscosity of 0.91. Plaques compression- The process f Example 13 was repeated but i this moulded at 200 C. from this material were transparent case h amount f N- h n l l i id w increased and amber in colour but showed a flexural breaking stress at the expense of olefine in the monomer mixture. The 75 of only 10.8 kg./mm. at 20 C.

15 EXAMPLE 22 2800 parts of water containing 4.17 parts by weight of dodecanethiol, 10.5 parts of potassium persulphate, 7.35 parts of sodium metabisulphite and 4.9 parts of sodium ty of 0.87. It could be compression-moulded to give very pale yellow, transparent plaques. It had a full Vicat softening point of 104 C. and a flexural breaking stress of 17.9 kg/mmP.

dodecyl sulphate were charged to an autoclave, together EXAMPLE 26 with 121.8 parts (5 mole percent) of N-phenylmaleimide N-2-chlorophenylmaleimide (20.75 g., 5 mole percent), and 556.5 parts (75 mole percent) of acrylonitrile. The acrylonitrile (99.7 cm. 75 mole percent) and propylene autoclave was then purged with nitrogen and vented as de- (27.6 cm. 20 mole percent) were copolymerised by the scribed in Example 15, and then 156.8 parts (20 mole process of Example 7 using potassium persulphate (1.5 percent of isobutene were added and the pressure raised 10 g.), sodium metabisulphite (1.056 g.), sodium dodecyl to 4.5 kg./cm. with nitrogen. Reaction was effected for sulphate (0.667 g.) and water (400 cm. in a shaking 4.33 hours at a temperature of 22-42 C. before the autoautoclave at 30 C. The product (82.6 g., 70% yield) clave was vented and the latex coagulated. After working was isolated as described in Example 7 and had a reup as described in Example 15, 760.3 parts were obtained duced viscosity of 1.50. On compression-moulding at 200 of a copolymer having a reduced viscosity of 1.08, and C. it produced transparent yellow plaques having onecontaining 73 mole percent of acrylonitrile, 21 mole pertenth and full Vicat softening points of 111 C. and cent of isobutene and 6 mole percent of N-phenyl- 127 C. respectively. The flexural breaking stress was maleimide. The polymer was compression-moulded at 12.2 kg./mm.

200 C. to give yellow transparent plaques having a flex- 2O EXAMPLE 27 ural breakmg Stress of The process of Example 26 was repeated on the same By W compzfltlson the experiment was repeated scale using ethylene gas at 10.8 kg./cm. in 740 cm. under identical conditions except that the amount of catworking volume mole Percent) instead of propylene. alyst was reduced to 8' Parts 9 pot'flsslum pefsulphate The isolated product (74.0 g., 66% yield) had a reduced and 5.84 parts of sodium metabisulphite. In this process viscosity of 625. On compressiommoulding at C. the tempiarature of Polymensatl? was to it produced transparent amber plaques having a one-tenth close limits and varied between 29.9 and 31.9 C. during Vicat Softening point of The flexural breaking the 4.33 hours of the reaction. After working up as de- Stress was 6.1 kg /mm.2 scribed in Example 15, 611.6 parts were obtained of a copolymer having a reduced viscosity of 1.70, and con- EXAMPLE 3 taining 74 mole percent of acrylonitrile, 19' mole percent of isobutene and 7 mole percent of N-phenylrnaleimide. N-phenylmaleimide 8- 5 H1016 P acryloni- Plaques compression-moulded from this copolymer were U116 631-3, 75 mole p and Styrene too tough to break in the flexural test at 20 c. and 20 mole p were copolymerised as described n showed a tensile yielding stress of 10.8 kg./mm. Exarrllpdle 2?. The reaction was extr m ly rapid to give EXAMPLE 23 gaielsgi. p0 ymer which was isolated (129 g., 93.5%

The process of Example 22 was repeated but in this EXAMPLE 29 case the catalyst com rised 5.25 arts of potassium persulphate and 3.67 part of sodium metabisulphite. Polym- 40 A ierpopolymer contammg 6 mole f f of N'Pheny erisation was effected at a temperature of 30.0-30.8 C. maleumde mole perciant of acrylomtnk 19 mole for 6 hours After Working up as described in Example perc ent of isobutene, which had a softening point above 15, 443.7 parts were obtained of a copolymer having a 100 and a flexural breakmg stless 9 18 reduced viscosity of 2.21, and containing 73 mole percent was blended on a steam'heated mlll Wlth. a Variety of of acrylonitrile, 19 mole percent of isobutene and 8 mole rubbers nature of the rubbers of whlch 35 W percent of N-phenylmaleimide. This was compressionblqnded Wlth 100 of Eercopolymel" the softenlng moulded at to give pale yellow transparent points of the blends obtained are shown in the following plaques having a flexural breaking stress of 17.8 kg./mm. table and a tensile yielding stress of 11.3 kg./mm. vicat'softenmg EXAMPLE 24 In this example several polymerisations were effected, Rubber Onetemh Fun each using the process of Example 22. In each case the Acrylqnitrilelbutadiene :67 mole percent) 101 10s amount of catalyst Was Constant at parts of potassium iit il ffllli ffll fiflf fy lffifl ii i3921 525- 104 110 persulphate and 5.84 parts of sodium metabisulphite but f l fiitg acrylate (:40m01e p c nt) g} 183 the amount and nature of the chain transfer agent were 55 ,i 'g 'zgggggg gbgggg 103 no varied. The results are set out in the following table, Polyethyl ecrylate 95 105 where A is the product already described in Example 22. Acrylomtme/butylacrylate (13:87 mole percent) 98 106 Polymer composition (mole percent) Yield of N-phen- Full Vicat Chain transfer agent copolymer, Reduced Aeryloylrnale- Isosoftening Flexural breaking (parts by weight) percent viscosity nitr'ilo imide butene Colour of moulding point, 0. stress 7,

A-.- Dodecanethiol (4.17) 73 1. 70 74 7 19 Pale yellow, transparent Too tough to test. B--. Dodeeanethiol (8.35) 82.3 1. 48 Not analysed do Not measured. 7 C... Thioglycollie acid (4.17)--- 1. 45 73 6 21 Amber, transparent 102 17.5 lrgJmm. YD--- Thiog1yc011icacid(8.35) 86.5 1.88 73 6 21 o 17.7 kgJmmfl E... Octanethiol (4.17)-. 73.2 0.91 72 7 21 Pale yellow, transparent" 109 16.7kg./1]11I1. Octanethiol (5.00).. 0. 74 72 s 20 0 17.2 k mm.= G Octancthiol (5.83) 79.2 0.7 71 S 21 Very pale yellow, 105 12.5 kg./mn1.' I-I.-. Octauethiol (6.68) 75 0.68 '73 6 21 Y c l l t i iir fi i z i dspai'ciit 105 15.8 kgJmin.

EXAMPLE 25 The process of Example 24 (E) was repeated with the N-phenylmaleimide replaced by 145.25 parts (5 mole percent) of N-2-chlorophenylmaleirnide. A copolymer Blends were similarly made with the following rubbers, using 42 g. per g. of tercopolymer:

(a) nitrile rubber containing a number of carboxy groups;

was obtained in 68.4% yield and having a reduced viscosi- 7 (b) acrylonitrile/butyl acrylate (20:80 mole percent);

(c) acrylonitrile/butadiene (40:60 mole percent), crosslinked; I p I I v (d) neoprene; f v v n (e) polybutadiene cross-linked with 1% divinyl benzene; and Q (f) ethylene/methyl methacrylate (48.52 mole percent).

I 7 EXAMPLE 30 Theilatex of a vtercopolymer of 5 mole 'percent.-of N- phenylmaleimide, 75 mole percent of acrylonitrile and 20 mole percent of isobutene was mixed with amounts of an acrylonitrile/butadiene (46:54 mole percent) rubber latex and the resulting latex blends were worked up to give products containing 5%, and by weight of rubber which were compression-moulded and showed full Vicat softening points of 111 C., 112 C., 108 C. and 107 C. respectively.

EXAMPLE 31 A sample of product F of Example 24 was dissolved in dimethyl formamide to yield a 12% solution. This solution was extruded through a filter to a spinneret through which it passed downwards into a heated air chamber maintained at about 60 C. to evaporate the solvent. The spun filament was collected on a rotating bobbin placed below the bottom of the chamber. The yarn so produced was slightly discoloured and still contained some solvent. Its tenacity could be increased by drawing at a temperature of about 110130 C.

EXAMPLE 32 A sample of a tercopolymer of 5 mole percent of N- phenylmaleimide, 75 mole percent of acrylonitrile and 20 mole percent of isobutene, having a reduced viscosity of 0.96 and a full Vicat softening point of 105 C. was injection-moulded at 280-285 C. in a single-screw preplasticising injection-moulding machine to give plaques 11.4 cm. in diameter and 0.32 cm. thick. The plaques conformed to the shape of the mould and were found to have a reduced viscosity of 0.93 and a full Vicat softening point of 108 C.

EXAMPLE 33 A series of terpolymer resins of acrylonitrile, styrene and N-o-chlorophenyl maleimide was prepared, and these terpolymers were subsequently blended with a commercial graft copolymer.

Resin 1.Acrylonitrile (42.8 g. 0.8 moles), styrene (107.3 g., 1.05 moles), N-o-chlorophenyl maleimide (16.5 g., 0.08 moles), sodium lauryl sulphate (5 g.), and mixed tertiary mercaptans (0.3 cm. were dispersed in 18 sodium dimethyl dithiocarbamate solution (6 cm?) at about conversion.

The resulting latex was coagulated into ethanol (1.5 dm. at 50 C., filtered, washed with water, and dried in vacuum. Yield was 224 g. of terpolymer having a reduced viscosity of 4.8. On compression moulding at 200 C., the terpolymer gave a transparent plaque having a Vicat softening point=126.8.

For comparison the softening point of a styrene/acrylonitrile copolymer containing 64.5 moles percent styrene was 106 C.

Resin 2.-The above process was repeated but n-octyl mercaptan (2.5 cm?) were used in place of the mixed tertiary mercaptans. Polymerisation was initiated with 5% ammonium persulphate solution (24 cm. 5% sodium metabisulphite solution (24 cm. and the reaction stopped at about conversion. Yield was 275 g. and the reduced viscosity was 0.39. The terpolymer produced transparent mouldings,

Resin 3.The process used for resin 1 was repeated using n-octyl mercaptan (1 cm?) in place of the mixed tertiary mercaptans. The reaction was initiated with 5% ammonium persulphate solution (15 cm?) and 5% sodium metabisulphite solution (15 cm?) and the second portion of the monomer added over the first 45 minutes of the reaction. Polymerisation was stopped at about 80% conversion, and the yield was 281 g. Transparent mouldings were produced from a terpolymer having a reduced viscosity of 0.79.

Resin 4.The process used for resin 3 was repeated using only 0.5 cm. of n-octyl mercaptan; 34 cm. of activator solutions were used. The polymerisation was stopped when the reaction temperature began to fall, which was at about conversion. Yield was 297.0 g., and the reduced viscosity was 1.12.

Resins 1 to 4 were blended with a. commercial graft polymer Blendex 301 comprising about 50 weight percent (60 mole percent) butadiene, 35 weight percent (22 mole percent) styrene and 15 weight percent (18 mole percent) acrylonitrile. The proportions are shown in the table below. Blends 1 and 2 were prepared by powder blending the resins and graft materials, and extruding at 200 C. with a screw speed of 80 r.p.m. in an extruder. The resulting lace was cut up and compression moulded at 200 C. to give opaque plaques.

To produce blends 3-5, the resin and graft material were mixed then blended on a steam-heated 6 x 2 inch (15.25.1 cm.) mill at 170l80 C. for 5 minutes. The resultant crepe was compression moulded at 200 C. as before.

The results of physical tests on the blends are shown below.

Vicat softening Notched poi t Yield stress impact strength Ratio by Resin weight Kg.f./ Blend used resln/graft $4 Full 10 p.s 1 mm 2 Lb./ln. .T./em.

1 1 50/50 116. 4 5. 5 3. 0 67 1. 17 2 2 50/50 107 B rlttle 3 3 50/50 107. 6 116. 2 5. 8 4. 1 59 1. 03 4 3 75/25 117 124. 4 8. 5 6. 0 24 0.42 5 4 50/50 109. 6 118 5. 5 3. 9 64 1. 12

water (800 cm. and the system put under nitrogen. EXAMPLE 34 The reaction was initiated at 28 C. by adding 5% ammonium persulphate (30 cm. and 5% sodium metabisulphite (30 cm. solutions to the vessel. An equal quantity of monomers, that is acrylonitrile (42.8 g.), styrene (107.3 g.), and N-o-chlorophenyl maleimide (16.5 g.), were added to the reacting mixture over a period of /2 hour. The reaction temperature was maintained at about 33 C. by addition of 0.1% sodium dimethyl dithiocar- A graft copolymer containing acrylonitrile, styrene and N-o-chlorophenyl maleimide in the grafted phase was prepared using a commercial polybutadiene latex, Firestone FR-S 2004 containing 61% solids. A mixture of the latex (181 g.), sodium hydroxide (0.1 g.) and water (374 cm?) were placed in a 2 dm. polymerisation vessel equipped with a stirrer and the air replaced by nitrogen.

bamate solution, and the reaction short stopped with 5% 75 The catalyst, potassium peroxydisulphate (1.0 g.) was added to the latex mixture and the temperature raised to 63 C. While maintaining the temperature substantially constant a mixture of acrylonitrile (32 g.), styrene (68.0 g.) and N-o-chlorophenyl maleimide g.) together with an emulsifier comprising the sodium salt of a disproportionated rosin acid (4.0 g), sodium hydroxide (0.12 g.) and water (62.0 cm?) was added to the reaction mixture over a period of 2 hours. After a further 40 minutes sodium formaldehyde sulphoxylate (0.6 g. in cm. of water) was added and the mixture allowed to cool. After standing overnight, coagulation was achieved by the addition of 10% acetic acid. The mixture was heated to 90 C. to increase the particle size, reslurried and 2,6-ditertiarybutyl 4-methyl phenol (11 g.) and dilauryl thiodipropionate (5.5 g.) in the form of suspensions were added as stabilisers. Acetic acid (10%, 20 cm.') was added and the mixture filtered. The residue was washed with water, and dried in a vacuum oven at C. to give a yield of 220 g.

EXAMPLE 35 The method of Example 34 was used to prepare a graft copolymer using a commercially available polybutadiene latex (Polysar 1 710) containing 63% solids in water (888 cm. with sodium hydroxide (0.2 g.) added. The emulsitier solution contained the sodium salt of a disproportionated rosin acid (8.0 g.) and sodium hydroxide (0.24 g.) in water (124 cm. The catalyst was potassium peroxydisulphate (2.0 g.). The monomer mixture contained acrylonitrile (64 g.), styrene (136 g.) and N-o-chlorophenyl maleimide (20 g.), and this mixture was added over a period of 3 /2 hours. After a further 2 /2 hours the heating and stirring were stopped and sodium formaldehyde sulphoxylate (1.2 g. in 20 cm. water) was added. The polymer was isolated as before and stabilised using 2,6-ditertiarylbutyl 4-methyl phenol (22 g. as 30% suspension) and dilaurylthiodipropionate (11 g. as 30% suspension). The yield was 390 g. of graft copolymer.

EXAMPLE 3 6 A series of blends of a number of graft copolymers and resins identified below was prepared by melt blending on a mill having 6 in. (15.2 cm.) x 2 in. (5.1 cm.) rolls at 170 C. and milled for approximately 5 minutes. The resulting crepe was cut into small pieces and compression moulded at 200 C. to give 6 in. (15.2 cm.) x 4 in. (10.2 cm.) x A" (0.32 cm.) plaques. The blends were as follows.

Blend lPolyvinyl chloride and terpolymer graft as prepared in Example 35, in the ratio 80:20.

Blend 2Diakon polymethyl methacrylate and terpolymer graft as prepared in Example 35 in the ratio :50.

Vicat softening Notched impact point, C. Yield stress strength ,10 Full 10 p.s.i. kg.f./m1r1. Lb./in. llcmfl EXAMPLE 37 Three blends were prepared using the terpolymer graft of Example 34 and resins as identified below. A ratio of 45.45 parts by weight of graft to 54.55 parts by weight of resin was used in each case. The constituents were melt blended on a mill having heated 6 in. (15.2 cm.) x 2 in. (5.1. cm.) rolls at 185 C., the resulting crepe being cut into small pieces and compression moulded at 200 C. for mechanical testing.

The resins used in the blends were as follows.

Blend lTerpolymer of acrylonitrile, a-methyl styrene and N-o-chlorophenyl maleimide prepared from monomers having a molar ratio 47/48.5/4.5 respectively, and having a reduced viscosity of- 0.67. v

Blend 2A mixture comprising 1) 45 g. of a terpolymer prepared according to Example 33 resin 3, and (ii) 10 g. of a terpolymer prepared according to Example 33 resin 4.

Blend 3Tyril 767 The results of the mechanical testing were as follows.

Blend 3.Commercial styrene/acrylonitrile copolymer (Tyril 767) having approximate molar ratio of 70/30 respectively, and terpolymer graft as prepared in Example 35 in the ratio 50:50.

Blend 4.Tyril 1 767 and Blendex 1 301 ABS graft in the ratio 50:50.

Blend 5. -Terpolymer of acrylonitrile a-methyl styrene and N-o-chlorophenyl maleimide prepared from monomers in the molar ratio 47/48.5/4.5 respectively having a reduced viscosity of 0.67, with terpolymer graft as prepared in Example 35 in the ratio 50:50.

Blend 6.Terpolymer as used in Blend 5 with Blendex 1 301 ABS graft in the ratio 50:50.

Blend 7.Terpolymer of acrylonitrile, styrene and N-ochlorophenyl maleimide as prepared in Example 33, resin 3, with terpolymer graft as prepared in Example 35 in the ratio 50:50.

Blend 8.-Bisphenol A polycarbonate and terpolymer graft as prepared in Example 35 in the ratio :25.

To blends 4 and 6, 2,6-ditertiary butyl 4-methyl phenol (1 g.) and dilaurylthiodipropionate (0.5 g.) were added to stabilse the composition.

The compression moulded plaques were used for the physical tests, the results of which are shown in thefollowing table. Y

Vicat softening Notched impact point, C. Yield stress Strength 540 Full 10 p.s.l. kg.i./mm. Lb./in. .T./em.

Blendex, Firestone FR-S, Polysar, Diakon and Tyril are trademarks of Marbon Chemical Division Borg Warner Limited, Firestone Synthetic Rubber and Latex Company, Polymer Corporation Limited, Imperial Chemical Industries Limited, and the Dow Chemical Company respectively.

We claim:

1. A graft copolymer consisting essentially of:

(A) a grafted superstrate of a copolymer consisting essentially of 1 to 50 mole percent of acrylonitrile, 1 to 98 mole percent of at least one conjugated aromatic olefin selected from the group consisting of styrene and methyl styrenes and 1 to 50 mole percent of at least one N-aryl maleimide in which the aryl group is selected from the group consisting of: phenyl, 4-diphenyl, l-naphthyl, methylphenyl, dimethylphenyl, 2,6-diethylphenyl, monoand dihalophenyl, 2,4,6-trichlorophenyl, 2,4,6-tribromophenyl, 4-n-butylphenyl, 2-methyl-4n-butylphenyl, 4-benzylphenyl, 2-, 3- and 4-methoxyphenyl, 2-methoxy-5-chlorophenyl, 2-, 3- and 4-ethoxyphenyl, 2,5-dimethoxy-4-chlorophenyl, 2-, 3- and 4-ethoxyphenyl, 2,5-diethoxyphenyl, 4-phenoxyphenyl, 4-methoxycarbonylphenyl, and methylchlorophenyl, and in which the molar ratio of aromatic olefin to acrylonitrile lies within the range 0.5 to 4 and the amount of said N-aryl maleimide is suiiicient that a polymer consisting of said superstrate has a substantially higher softening point than a corresponding polymer which does not contain said N=aryl maleimide on (B) a substrate of a diene rubber containing (i) 40 to 100 mole percent of at least one conjugated 1,3-diene selected from the group consisting of butadiene, isoprene, 2,3-dimethylbutadiene, piperylene and chloroprene and (ii) from 0 to 60 mole percent of units 21 of at least one ethylenically unsaturated copolymerizable monomer selected from the group consisting of styrene, a-methylstyrene, methyl, ethyl, n-butyl and Z-ethylhexyl acrylates, and methyl and n-butyl methacrylates, and acrylonitrile.

2. A blend consisting essentially of:

(I) a copolymer consisting essentially of (A) a grafted superstrate of a copolymer of acrylonitrile and at least one conjugated aromatic olefin selected from the group consisting of styrene and methyl styrenes in which the molar ratio of conjugated aromatic olefin to acrylonitrile lies within the range 0.5 to 4 on (B) a substrate of a diene rubber containing (i) 40 to 100 mole percent of at least one conjugated 1,3-diene selected from the group consisting of butadiene, isoprene, 2,3-dimethylbutadiene, piperylene and chloroprene and (ii) from to 60 mole percent of units of at least one ethylenically unsaturated copolymerizable monomer selected from the group consisting of styrene, u-methylstyrene, methyl, ethyl, n-butyl and 2-ethylhexyl acrylates, and methyl and n-butyl methacrylates, and acrylonitrile, and

(II) a copolymer in which the units consist essentially of l to 50 mole percent acr'ylonitrile, 1 to 98 mole percent of at least one conjugated aromatic olefin selected from the group consisting of styrene and methyl styrenes, 1 to 50 mole percent of at least one N-aryl maleimide in which the aryl group is selected from a group consisting of phenyl, 4-diphenyl l-naphthyl, methylphenyl, dirnethylphenyl, 2,6-diethylphenyl, monoand dihalophenyl, 2,4,6-trichlorophenyl, 2,4,6 tribrornophen'yl, 4 n butylphenyl, Z-methyl-4-n-butylphenyl, 4-benzylphenyl, 2-, 3- and 4-methoxyphenyl, Z-methoxy-S-chlorophenyl, Z-methoxy-S-bromophenyl, 2,5-dimethoxy-4-chlorophenyl, 2-, 3- and 4-ethoxyphenyl, 2,5-diethoxyphenyl, 4-phenoxyphenyl, 4-methoxycarbonylphenyl, and methylchlorophenyl and in which the molar ratio is conju gated aromatic olefin to acrylonitrile lies within the range 0.5 to 4 and the amount of said N-arylmaleimide is suflicient that said copolymer has a substantially higher softening point than a corresponding polymer whtch does not contain said N-aryl maleimide,

said blend containing 1-50% by weight rubber.

3. A blend consisting essentially of:

'(I) a graft copolymer according to claim 1 and (II) a copolymer in which the units consist essentially of 1 to 50 mole percent acrylonitrile, 1 to 98 mole percent of at least one conjugated aromatic olefin selected from the group consisting of styrene and methyl styrenes, 1 to 50 mole percent of at least one N-aryl maleimide in which the aryl group is selected from the group consisting of: phenyl, 4-diphenyl, l-naphthyl, methylphenyl, dimethylphenyl, 2,6-diethylphenyl, monoand dihalophenyl, 2,4,6-trichlorophenyl, 2,4,6 tribromophenyl, 4 n butylphenyl, 2Inethyl-4-n-but'ylphenyl, 4-benzylphenyl, 2, 3- and 4-methoxyphenyl, 2-methoxy-S-chlorophenyl, 2-methoxy-S-bromophenyl, 2,5-dimethoxy-4-ch1orophenyl, 2-, 3- and 4-ethoxyphenyl, 2,5-diethoxyphenyl, 4-phenoxyphenyl, 4-methoxycarbonylphenyl, and methylchlorophenyl and in which the molar ratio of conjugated aromatic olefin to acrylonitrile lies within the range 0.5 to 4 and the amount of said copolymer is sufficient that said copolymer has a substantially higher softening point than a corresponding polymer which does not contain said N-aryl maleimide, said blend containing 1-50% by weight rubber.

4. A blend consisting essentially of a graft copolymer according to claim 1 and a copolymer of acrylonitrile and at least one conjugated aromatic olefin in which the molar ratio of conjugated aromatic olefin to acrylonitrile lies within the range of 0.5 to 4.

5. A blend consisting essentially of a graft copolymer according to claim 1 with polyvinyl chloride in which the weight ratio of graft copolymer to polyvinyl chloride is chosen so that the amount of rubber the blend contains is 1 to 50%.

6. A blend consisting essentially of a graft copolymer according to claim 1 with polymethyl methacrylate in which the weight ratio of graft copolymer to polymethyl methacrylate is chosen so that the amount of rubber that the blend contains is 1 to 50%.

7. A blend consisting essentially of a graft copolymer according to claim 1 with a polycarbonate of 4,4'-isopropylidenediphenol in which the weight ratio of graft copolymer to polycarbonate is chosen so that the amount of rubber the blend contains is l to 50%.

References Cited UNITED STATES PATENTS 3,352,832 11/1967 Barr et a1 260-78 HAROLD D. ANDERSON, Primary Examiner U.S. Cl. X.R.

260-4 AR, 29.6 RW, 29.6 TA, 32.6 N, 41 R, 47 UA, 78 UA, 78.5 BB, 873, 879, 889, 896, 897 B 

